view tests/test-filebranch.t @ 36755:ff4bc0ab6740 stable

wireproto: check permissions when executing "batch" command (BC) (SEC)

For as long as the "batch" command has existed (introduced by
bd88561afb4b and first released as part of Mercurial 1.9), that command
(like most wire commands introduced after 2008) lacked an entry in
the hgweb permissions table. And since we don't verify permissions if
an entry is missing from the permissions table, this meant that
executing a command via "batch" would bypass all permissions
checks.

The security implications are significant: a Mercurial HTTP server
would allow writes via "batch" wire protocol commands as long as
the HTTP request were processed by Mercurial and the process running
the Mercurial HTTP server had write access to the repository. The
Mercurial defaults of servers being read-only and the various web.*
config options to define access control were bypassed.

In addition, "batch" could be used to exfiltrate data from servers
that were configured to not allow read access.

Both forms of permissions bypass could be mitigated to some extent
by using HTTP authentication. This would prevent HTTP requests from
hitting Mercurial's server logic. However, any authenticated request
would still be able to bypass permissions checks via "batch" commands.

The easiest exploit was to send "pushkey" commands via "batch" and
modify the state of bookmarks, phases, and obsolescence markers.
However, I suspect a well-crafted HTTP request could trick the server
into running the "unbundle" wire protocol command, effectively
performing a full `hg push` to create new changesets on the remote.

This commit plugs this gaping security hole by having the "batch"
command perform permissions checking on each sub-command that is
being batched. We do this by threading a permissions checking
callable all the way to the protocol handler. The threading is a
bit hacky from a code perspective. But it preserves API compatibility,
which is the proper thing to do on the stable branch.

One of the subtle things we do is assume that a command with an
undefined permission is a "push" command. This is the safest thing to
do from a security perspective: we don't want to take chances that
a command could perform a write even though the server is configured
to not allow writes.

As the test changes demonstrate, it is no longer possible to bypass
permissions via the "batch" wire protocol command.

.. bc::

   The "batch" wire protocol command now enforces permissions of
   each invoked sub-command. Wire protocol commands must define
   their operation type or the "batch" command will assume they
   can write data and will prevent their execution on HTTP servers
   unless the HTTP request method is POST, the server is configured
   to allow pushes, and the (possibly authenticated) HTTP user is
   authorized to perform a push.

This test makes sure that we don't mark a file as merged with its ancestor
when we do a merge.

  $ cat <<EOF > merge
  > from __future__ import print_function
  > import sys, os
  > print("merging for", os.path.basename(sys.argv[1]))
  > EOF
  $ HGMERGE="$PYTHON ../merge"; export HGMERGE

Creating base:

  $ hg init a
  $ cd a
  $ echo 1 > foo
  $ echo 1 > bar
  $ echo 1 > baz
  $ echo 1 > quux
  $ hg add foo bar baz quux
  $ hg commit -m "base"

  $ cd ..
  $ hg clone a b
  updating to branch default
  4 files updated, 0 files merged, 0 files removed, 0 files unresolved

Creating branch a:

  $ cd a
  $ echo 2a > foo
  $ echo 2a > bar
  $ hg commit -m "branch a"

Creating branch b:

  $ cd ..
  $ cd b
  $ echo 2b > foo
  $ echo 2b > baz
  $ hg commit -m "branch b"

We shouldn't have anything but n state here:

  $ hg debugstate --nodates | grep -v "^n"
  [1]

Merging:

  $ hg pull ../a
  pulling from ../a
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 2 changes to 2 files (+1 heads)
  new changesets bdd988058d16
  (run 'hg heads' to see heads, 'hg merge' to merge)

  $ hg merge -v
  resolving manifests
  getting bar
  merging foo
  merging for foo
  1 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ echo 2m > foo
  $ echo 2b > baz
  $ echo new > quux

  $ hg ci -m "merge"

main: we should have a merge here:

  $ hg debugindex --changelog
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0      73  .....       0 cdca01651b96 000000000000 000000000000 (re)
       1        73      68  .....       1 f6718a9cb7f3 cdca01651b96 000000000000 (re)
       2       141      68  .....       2 bdd988058d16 cdca01651b96 000000000000 (re)
       3       209      66  .....       3 d8a521142a3c f6718a9cb7f3 bdd988058d16 (re)

log should show foo and quux changed:

  $ hg log -v -r tip
  changeset:   3:d8a521142a3c
  tag:         tip
  parent:      1:f6718a9cb7f3
  parent:      2:bdd988058d16
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       foo quux
  description:
  merge
  
  

foo: we should have a merge here:

  $ hg debugindex foo
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       3  .....       0 b8e02f643373 000000000000 000000000000 (re)
       1         3       4  .....       1 2ffeddde1b65 b8e02f643373 000000000000 (re)
       2         7       4  .....       2 33d1fb69067a b8e02f643373 000000000000 (re)
       3        11       4  .....       3 aa27919ee430 2ffeddde1b65 33d1fb69067a (re)

bar: we should not have a merge here:

  $ hg debugindex bar
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       3  .....       0 b8e02f643373 000000000000 000000000000 (re)
       1         3       4  .....       2 33d1fb69067a b8e02f643373 000000000000 (re)

baz: we should not have a merge here:

  $ hg debugindex baz
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       3  .....       0 b8e02f643373 000000000000 000000000000 (re)
       1         3       4  .....       1 2ffeddde1b65 b8e02f643373 000000000000 (re)

quux: we should not have a merge here:

  $ hg debugindex quux
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       3  .....       0 b8e02f643373 000000000000 000000000000 (re)
       1         3       5  .....       3 6128c0f33108 b8e02f643373 000000000000 (re)

Manifest entries should match tips of all files:

  $ hg manifest --debug
  33d1fb69067a0139622a3fa3b7ba1cdb1367972e 644   bar
  2ffeddde1b65b4827f6746174a145474129fa2ce 644   baz
  aa27919ee4303cfd575e1fb932dd64d75aa08be4 644   foo
  6128c0f33108e8cfbb4e0824d13ae48b466d7280 644   quux

Everything should be clean now:

  $ hg status

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  4 files, 4 changesets, 10 total revisions

  $ cd ..